1. Field of the Invention
This invention relates to optical fiber cables having cable jackets with non-circular cavity cross sections for improved crush resistance.
2. Background Art
The background art shows cable jackets having non-circular cross-sectional shapes for both the outer periphery and cavity thereof. Moreover, the background art associates improved crush resistance with such non-circular shapes.
A paper by Stevens et al., entitled "FINITE ELEMENT MODELING OF OPTIC FIBER CABLE CRUSH PERFORMANCE" (IWCS, November 1998), provides an analysis of elastic-plastic deformations of thermoplastic cable elements using finite element modeling. This paper is incorporated herein by reference. The cable elements considered in the above paper included non-circular cross sections. The authors concluded that by changing the shape from a circular to an elliptical or rectangular cross-section, the cable can have improved crush resistance, lower weight and better unidirectional flexibility.
Blew et al. (U.S. Pat. No. 5,651,081) disclose an optical fiber cable having a non-circular outer periphery and a circular cavity. See, e.g., FIG. 4 of Blew et al.
Cables having a non-circular outer periphery exhibit greatly improved crush performance but may pose cable closure compatibility problems, product marketing and/or customer perception problems as compared to cables having a conventional circular outer periphery.
Dean et al. (U.S. Pat. No. 4,420,220) disclose an optical fiber cable having a circular outer periphery and a non-circular cavity. See, e.g., FIG. 3 of Dean et al. However, in Dean et al., the non-circular cavity is oriented such that its major axis coincides with a line extending between the strength members. Consequently, this fiber cable exhibits relatively poor crush resistance in a direction transverse to the line extending between the strength members.